The present invention relates to cam actuators and more particularly to cam actuators providing an adjustable stroke.
In the manufacture of creme filled sandwiches and the like, the filling material is extracted from a hopper by pistons mounted in a thick walled drum rotating beneath the hopper. As the pistons move under the hopper, they are moved inwardly to draw a slug of filling into the piston cylinder. The drum is mounted above a conveyor belt carrying base cakes. As the drum rotates carrying the pistons from the hopper downwardly, the pistons are extended to move the slug of filling to a position external of the drum so it can be removed and dropped onto a base cake.
The radial motion of the pistons is controlled by a cam mounted coaxially within the drum. The pistons have cam following rollers on their inner ends. The pistons are spring loaded to hold the cam followers against the cams.
It is desirable to be able to vary the thickness of the creme filling so that different varieties of creme sandwiches can be produced on the same equipment.
In the past, this has been accomplished by providing the cams with a particular shape and by adjusting the rotational position of the cam with respect to the hopper. The cam was formed so that as the piston passes under the hopper, it is retracted to withdraw a thick slug of filling and then begins to gradually extend. The thickness of the slug placed on the base cake was determined by the radial position of the piston as it moved past a wiper at the exit edge of the hopper. The gradual extension normally began before the piston reached the wiper and continued after the piston had moved past the wiper.
With this arrangement, the thickness of the slug was increased or decreased by rotating the cam to increase or decrease the thickness of the slug as it passed under the wiper.
This arrangement had the disadvantage of producing tapered slugs of filling which resulted in sandwiches in which the upper and lower base cakes were nonparallel. The taper of the slug was caused by the continued radial motion of the piston as it passed under the wiper. The thickness of the slug at the leading edge was determined by the spacing between the leading edge of the piston and the wiper as it passed underneath. Likewise, the thickness of the slug at the trailing edge was determined by the space between the wiper and the trailing edge of the piston as that edge passed underneath.
In order that the slug be of uniform thickness from its leading edge to its trailing edge, it is necessary that the piston not move in the radial direction as it passed under the wiper.